The present invention relates to a motion absorbing conveyance system for transferring personnel and/or objects between a floating vessel and an installation, for example, an oil platform, in accordance with the preamble of claim 1, cited hereafter. The invention also relates to a method of forming a walkable connection between a floating vessel and an installation.
There are currently employed a number of different arrangements to provide for the transfer of personnel and goods between a floating vessel and an offshore platform. Due to the relative movement between the floating vessel and the platform, strong demands are made on these types of conveyance systems. There have previously been used baskets suspended on a crane boom, where the basket is hoisted by means of a winch equipped with a heave compensator system. Hoistable baskets of this type, however, represent a high safety risk, as the relative movements between the vessel and the platform can easily cause the basket to strike against the vessel or the platform with considerable force. There is also a risk that the basket will tip over on landing, causing personnel and/or goods to fall out. Between platforms there have also been used gangways, which form a rigid connection between these platforms. These gangways, however, are not suitable for transferring personnel between a platform and a floating vessel when the relative movements are heavy.
Examples of known art are shown in NO 145,131, NO 151,579, 157,255, U.S. Pat. Nos. 3,008,158, 4,011,615 and 4,169,296. For example, U.S. Pat. No. 4,169,296 shows the use of a ball joint between the outer end of the gangway and the platform. NO 145,131, for example, shows the utilization of a pull-down wire to draw the outer end of the gangway down to the platform. None of these publications, however, suggests the possibility of using a pull-down wire in combination with a ball joint. Furthermore, all the known arrangements have the disadvantage that the gangway is self-supporting. Nor is it possible to transfer cargo of any significant weight or size along the gangway connection.
Therefore, there is a great need for a far more secure conveyance system which can form a safe, walkable connection between a floating vessel and an installation, and which at the same time is adapted to be capable of transferring cargo between two installations. Thus, according to the invention there is provided a motion absorbing conveyance system in accordance with the characterizing clause of the following claim 1. In addition, there is provided a method in accordance with the characterizing clause of the subsequent claim 6.